09 March, 2017

Adding hot bed BQ Hephestos 3D Printer: Compiling and installing new firmware

If we want to print in ABS, heated table need

There are instructions on how to do this on the official website of Spain BQ, but are outdated and only explain how to do it in version 1.4.2 , which differs substantially from the latest firmware more refined versions , such as 2.3.1 or 2.4.0 ( do not not try it with 2.4.0, it gives compilation error at the very beginning).

Well, in short, I will show how to compile the firmware to serve you for these and subsequent versions , with optional hot bed activated and working properly. But first, I show how I've ridden (and there tutos on youtube so I save this part - The guy in this video , although physical and clothing clavadito me, not me lol).
A clause ... is a company of the stature of BQ should have precompiled firmwares with different options , and let the user choose (even versions with height sensors for self - calibration table), it is outrageous that a user who does not have know anything about compilers, have to eat the head ... even though deep down that is when you ride a printer that whole piece yourself ... but it is a trifle compile and save many headaches (there are several threads forums questions about this topic).
Before anything else, apart from the table, cables and thermistor, to feed the table need a power supply of at least 12V 8A ( best of 11 or more); the more heat amps before the table and more easily keep you warm. The most economical and reliable is to use an old power source ATW at least 300W, by looking at the indicating amperes for connection + 12V, are durable and well refrigerated fan:

To turn on the power, simply bypass the green wire with a black, or better put a switch on if you want to leave it off when you wear PLA:

The plate BQ bring printers bring a MOSFET with heatsink 20A can handle perfectly , but better to avoid passing all that power by feeding the Arduino 2560 board and do apart with a relay.

This is the electronic solid state relay that will use up about 80A peak.
When using a relay independently of the Ramps / Arduino electronics, you can also use a source other voltage (5 to 20V) because all the energy is converted into heat, we discuss Watts, if the transformer is 12V we 132W and 11A, with an atmosphere of 20 ° C is enough to warm the bed in 3 minutes keep warm at 70, although obviously you take less the more powerful. BQ sells one of 25A for 30 €.

To operate power to the relay, I have bridged two wires from the main power to the bed, in the green power terminal block (the relay does not consume almost anything, so it can be thin wires):
Below left, indicated by V + and V- feeding large bed

I will not go into too much detail in the placement of the table; not to stir too leads me what I did was to prepare the first where happen so that they could be bent without stretching or caught anywhere by moving the table back and forth and back.

The thermistor is connected bed right next to the thermistor injector, gives the same polarity
I used Kapton tape to tie them together and stiffen the set , and each cable not to walk by.

Then I cut calculating that with maximum extension, something left over cable , passing beneath into place each:

Then I've soldered them, with the thermistor stuck in the hole and protected too (at this point it is convenient to put on the other a piece of Kapton tape and transparent silicone to fix the thermistor) 

and finally we tied well with Kapton tape.

The bed is then tied with springs and screws replacing the original base , and just below the glass. The glass isolated over a little heat, and there are people who directly use hot base without glass at a lower temperature, but I don't recommend it, sooner or later we will damage the tracks that hot. 

I have placed the relay in the back, when fed 12V it triggers on the flow of current, which directly feeds the hot bed. One pole transformer to feed the bed is connected directly, and the other int the relay switch. Once everything is connected and updated the firmware, you can leave just below the electronic board, but fixed with a plastic hose:

It is necessary to tie the relay so it will not move with the movement of the cables to the table

To connect the power to the table I used a MOLEX female connector, to disconnect in the necessary maintenance (the yellow cable is ATX 12V source):

And now the hard time... compiling the firm with support for the table

First of all, download the source code from github repository 2.3.1 BQ, (or the latest version where they  are different updates ), it is the "source code (zip)" file. 2.4.0 I not compiled with me (missing files)
We unpack in a folder, where da same, but it is advisable to leave for example. C: \ Marlin to simplify the steps.
Requires Arduino installed in C: \ (see instructions in the documentation of the web) , plus  USB drivers, so we installed in C: \ Arduino with drivers (which also allows us to easily find out which COM port is assigned tools -> Port to open the IDE, you need to know to start compiling).
Installs finally open code compiler Make for Windows, downloading it from this site .
Recently they have made improvements so that the same code support all BQ printers (bravo for them, easier to maintain and improvements apply to all), so that before compilation we asked for the printer model (Hephestos in my case), language (Spanish) and COM port Windows has assigned to the printer.
It is no longer necessary as in previous versions use the Arduino IDE, have created a script that does it all for us; compiles and flash directly, making sure that everything went well. 

For the warm bed to work, we need to make a couple of changes in the configuration.h file  that is within our printer folder, in my case \ Marlin \ config \ hephestos. If you see complicated, here you can download and modified sources  for this printer, version 2.3.1, which only need to compile. 

We need to find and uncomment (remove the two principle //): 


And finally change this text 0 for 1 : 

#define TEMP_SENSOR_BED 0 -> #define TEMP_SENSOR_BED 1 

Save the file and we can compile. First of all, connect the USB cable from the card to the computer, and open a command window with 'cmd' and running it as administrator (usually in the Startup folder -> 'System Windows' in Win10 or accessories in Win7 and earlier). 

We write in the command window:

Cd .. ' until we get to the root C: \ (if we are not in C :, change with 'C').

Cd Marlin ' (the directory where the files to compile left)

run 'make.cmd ' (all without the quotes), and answer the questions (model, language and COM port number, as we have said above we can check with the Arduino IDE).

If you've installed everything correctly, the IDE and the GNU Make installed properly , you should be to compile and within seconds get to burn the firmware on the plate (you'll see the flashing lights of the plate communicating through the serial port). The command window will look something like this:

Now, when you restart the printer, you will see a change on the screen :
Previously with the previous firmware we saw this:

And now we see this , indicating the temperature of the bed and the desired temperature by the program to the right of the bar (and will not get printed to achieve, and which is set in the generator program Gcode like Cura or another):

Keep in mind that the previous programs, made no warm bed, not activated, so not worth us to ABS or other requiring warm bed.
I use different profiles in the Cura, one for PLA, one for ABS and another for Filaflex (facilitates the task of change of material); 
  • In the Advanced Settings tab, indicate that it has hot table (Hotbed).
  • Completely deactivate the cooling fan, it is better to cool slowly to avoid cracking (it is extremely hard).
  • Injection temperature 235 ° C and at 70 table.

The ABS to grip it tightly to the glass is best to mix acetone with traces of ABS in a ratio 6/1 (expected to go dissolving) in a spray to spray on the glass (if still not well attached, a polished glass or frosted white grips better).

The PLA to be environmentally friendly and cheaper, I use for prototyping or confectionery pieces or children 's toys (non - toxic), whereas the ABS for more durable and resistant parts that are exposed to moisture or want to last more than 2 years with high humidity (the PLA for its organic nature from sugars, moisture becomes brittle and then dissolves).
In addition the ABS , if we print in a closed and much much local generates noxious fumes, so it is advisable to keep ventilated, but without sudden changes in temperature, q ue it become brittle during printing.


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